The present invention relates to a new and improved transport or feeding apparatus for conveying a perforated recording medium to a platen or the like, and also relates to a new and improved method of using the inventive transport apparatus for conveying a recording medium perforated on both sides or margins to an office recording machine or the like.
In its more specific aspects, the invention specifically relates to an improved transport or feeding apparatus for conveying a perforated recording medium to a platen or the like, which transport or feeding apparatus contains a driveable endless transport or conveyor belt provided with entrainment or driving prongs or sprockets and extending around two rollers. An infeed run or strand of the transport belt together with a guide surface or face defines a conveying gap, and the conveying gap can be opened for the purpose of introducing the recording medium.
The perforated recording media, for example, may be constituted by continuous or endless forms or form sets and are typically supplied to a typewriter, to an automatic printer or to an accounting or bookkeeping machine. However, it is also possible to use such transport or feeding apparatus for supplying recording media to the printer of a data processing apparatus or of a recording instrument. Usually two such transport apparatuses are arranged in a mirror-image relationship in a paper feeder so as to engage the marginal perforations on both sides of the paper for transport or feeding purposes. The drive thereof occurs by means of the platen or the like which is also driven.
The transport apparatuses, which are also called tractors, are usually arranged above the platen in an oblique position which is rearwardly inclined. The paper is thus supplied to the platen from the same direction as usually is the case during manual introduction or infeed thereof. During this operation that strand or run of the transport or conveyor belt which is rearwardly and downwardly inclined serves as the infeed or supply run or strand while the run or strand which is forwardly and upwardly inclined serves as the outfeed run or strand for the paper which has been written upon. Guide surfaces or faces are located opposite the two runs or strands and together with the transport or conveyor belt each limit a respective conveying or feed gap for the paper, in order to ensure that the prongs of the transport or conveyor belt remain engaged with the marginal perforations of the paper. Due to the position of the infeed run or strand the insertion of the starting portion of the paper is rendered more difficult because the prongs on the side of the infeed run or strand are positioned outside the field of view of the operator.
To facilitate the insertion of the paper web into the underside of the two tractors, it is known, for example, from European patent publication No. 0,049,016 Al, to pivot the tractors together with the guide surfaces upwardly about the upper one of their shafts or axes to such an extent that the infeed runs forwardly and upwardly. The pivot angle required therefor is hardly less than 180.degree..
To insert the paper web in the prior art equipment it is necessary to tilt open the guide surfaces which bound the conveying gaps at both tractors, to pull the starting portion of the paper web from the rear so as to pass through beneath the tractors and again upwardly in front of the tractors, so as to register and engage the marginal perforations thereof with the prongs of the transport or conveyor belts, and then to again reclose the two guide surfaces. In the known design the guide surfaces are arranged at flaps connected to the tractors and which can be laterally opened. Subsequently, the tractors must be again pivoted into their operative position.
While the prior art design facilitates the immediate or direct attachment of the starting portion of the web with the prongs, a series of disadvantages is associated therewith. In addition to the relatively large number of required manipulations, it is tedious and cumbersome to pull the starting portion of the web so as to pass through below the tractors and to again pull the same upwardly in front of such tractors. On re-pivoting the tractors back into their operative position, the paper web which has been threaded through has to be pulled back again to some extent by hand, since otherwise there exists the danger that the excess length of the paper web will be clamped between a stop and the tractors and becomes crimped or folded. In addition to the aforementioned manipulations, it is then still required to also insert the starting portion of the paper web into the return conveying gap or space.
The large space requirements needed for pivoting the two tractors through a relatively large angle constitutes a further disadvantage of the known design.
In a further construction of transport apparatus for perforated recording media as known, for example, from British patent publication No. 2,023,552A, two transport or conveying units are provided on both sides of the paper web and which engage the perforations. One of the two transport or conveying units comprises an endless transport or conveyor belt provided with driving prongs, while the other of the two transport or conveying units comprises a transport or conveying wheel provided with entrainment prongs. One of the two transport units is arranged in front of the platen and the other one is arranged so as to follow the platen, in order to enable the paper web to be conveyed in both directions as required, for example, for graphic representations.
It is a disadvantage of the transport or conveying wheel of the known transport apparatus that only a small number of entrainment prongs simultaneously engage the marginal perforations of the paper web. This has the inherent danger that the marginal perforations become damaged or even torn. The result can be achieved that a larger number of entrainment prongs simultaneously engage with the marginal perforations by increasing the enclosing or wrap angle around the transport or conveying wheel. However, in such an arrangement there is increased the drawback which results from the different radius when a thick form set is used. Due to the difference in the radii between the inner and the outer sheets in such a form set the faultless engagement of the entrainment prongs with the perforations of the outer sheet is not ensured.
A further disadvantage of the aforementioned transport apparatus is the large distance prevailing between the transport or conveying wheel and the platen. This large distance, on the one hand, makes the insertion difficult and impairs the accuracy of exactly filling-in the pre-printed form sets, on the other hand, if the transport or conveying wheel is intended to define the exact position.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind it is a primary object of the present invention to provide a new and improved transport apparatus for conveying a perforated recording medium to a platen or the like, which enables the operator viewing the platen contained in the machine in front of him or her to properly position and insert the starting portion of a recording medium and to operatively drivingly connect the perforations thereof to the entrainment or driving prongs.
Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the transport apparatus of the present development is manifested by the features that, an insertion or threading roller provided with prongs or sprockets or the like and driveable at a circumferential speed synchronous with the transport or conveyor belt is positioned in a fixed reference position with respect to the conveying or feed gap and forwardly thereof on the side of the guide surface, and the transport or conveyor belt and the guide surface are pivotable relative to each other about the shaft or axis of the roller which is at a further distance or more remote from the insertion or threading roller in order to open the conveying gap.
For introducing the starting portion of the paper into the inventive transport apparatus only the conveying gap or space has to be opened, the starting portion of the paper must be inserted, while positioning the perforations thereof, onto the prongs of the insertion or threading roller, and the conveying gap is again closed.
The conveying gap or space can either be opened or closed by pivoting the transport or conveyor belt relative to the guide surface or, respectively, by pivoting the guide surface relative to the transport or conveyor belt. The insertion or threading roller is arranged in a fixed reference position with respect to the guide surface, i.e. the insertion or threading roller is pivotable together with the guide surface in the event that the guide surface is constructed to be pivotable. In case that the conveyor belt is pivotable the guide surface and the insertion or threading roller are stationarily arranged.
The insertion roller, which is placed forwardly of the conveying gap and which serves as a positioning roller, ensures that the perforations on the guide surface are exactly aligned, so that the entrainment or driving prongs of the transport or conveyor belt faultlessly engage the perforations when the conveying gap is closed. It is thus not necessary for the operator to have visual access to the entrainment or driving prongs of the transport or conveyor belt.
The pivoting range of the parts or members which are pivotable relative to each other is relatively small like, for example, 30.degree., so that no substantial free space is required therefor.
Even when the prongs or the like of the insertion roller remain engaged with the perforations during operation, the tensional force is transferred to the paper web substantially by the action of the driving or entrainment prongs of the transport or conveyor belt. However, the transport or conveyor belt will only contact the paper web along a straight path so that the difficulties mentioned heretofore with reference to thick form sets and occurring when the paper web is forced around in correspondence to the radius of a roll are not present in the transport apparatus according to the invention.
One of the important inventive concepts thus essentially resides in the features that the paper web together with the perforations thereof are applied from above, and specifically within the field of view of the operator, to prongs or the like serving for positioning the same, namely the prongs of the insertion roll, although the entrainment or driving prongs of the tractor effective for the transport operation engage the perforations from the opposite side. Furthermore, the pivotability of either the tractor or of the guide surface is utilized to open the conveying gap or space, so that a separately operated flap becomes superfluous.
In a preferred embodiment of the transport apparatus according to the invention, the guide surface and the insertion roller or roll are arranged stationary and the transport conveyor belt is pivotably arranged. The paper web is thus prevented from moving when the conveying gap or space is closed, so that the same cannot become crushed or upset and also cannot slide-off the prongs of the insertion roller. There is furthermore avoided with such design that the drive elements for the insertion roller must be pivoted.
According to a further design of the transport apparatus according to the invention, the insertion roller is arranged tangentially forwardly of the conveying gap. The advantage thereof is that a linear infeed of the paper web from the tangent of the insertion roller into the conveying gap is thus obtained. However, such an arrangement is not absolutely required.
In another preferred design of the transport apparatus according to the invention, the guide surface possesses an extension or prolongation extending into the region adjacent the circumferential surface of the insertion roller and having a curvature in this region which at least approximately corresponds to the circumferential surface of the insertion roller. With this design there is present a table-like surface or plane adjacent the insertion roller which passes from the circumferential surface of the insertion roller into the plane of the conveying gap or space. Such a surface serves to support the paper web and facilitates the manual holding of the paper web until the conveying gap is closed.
According to another design of the transport apparatus according to the invention the pivoting shaft or axis also is the driving shaft or axis for the transport or conveyor belt. Thus, the driving shaft or axis of the tractor is that shaft or axis which is closest to the platen. In addition to the advantage that the pivot shaft or axis simultaneously also constitutes the driving shaft or axis, there results the further advantage that the transmission elements required between the driven platen and the driving shaft of the tractor are positioned relatively close to each other.
According to a still further design of the transport apparatus according to the invention for simultaneously guiding the recording medium away from the platen a further guide surface is arranged at a stationary linked or hingedly mounted flap and opposite to the other run or strand of the transport or conveyor belt, in order to define a further conveying gap. Accordingly, the further guide surface associated with the outfeed run or strand is not pivotably connected to the tractor, but is stationarily and pivotably linked or connected. In this case the pivoting shaft or axis preferably extends parallel to the transport or conveying direction, so that the flap can be laterally pivoted away. The arrangement may be carried out such that the flap, during pivoting of the tractor in order to open the insertion gap, is conjointly pushed open. In such case the flap is already open without requiring any additional manipulations when the starting portion of the paper web is applied to the outfeed run or strand of the transport or conveyor belt after having been extended around the platen.
The invention also contemplates a method of using the transport apparatus of the present development, which is manifested by the features that, the transport apparatus is used for infeeding a recording medium which is perforated on both of its sides or margins to an office recording machine, wherein two mirror-symmetrically structured transport apparatuses are arranged each to one side of a guide path or guideway, and each respective driven roller and insertion roller thereof are fixed arranged for rotation but axially displaceable upon respective common shafts.